Preparation method of cyanuric fluoride

Abstract

The invention discloses a preparation method of cyanuric fluoride, which comprises the following steps: S1, preparation of a cyanuric chloride solution: dissolving cyanuric chloride into a solvent to obtain the cyanuric chloride solution; s2, preparation of mixed gas: diluting fluorine gas with inert gas to obtain the mixed gas; and S3, fluorination reaction: in the continuous microreactor, enabling the cyanuric chloride solution and fluorine in the mixed gas to react to generate cyanuric fluoride. The method does not need a catalyst, is short in reaction time, high in preparation efficiency, simple in process, low in cost, few in three wastes, high in product yield and suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the field of chemical synthesis, and in particular to a method for preparing cyanuric fluoride. Background Art

[0002] Cyanuric fluoride is a fluorine-containing chemical, also known as 1,3,5-trifluoro-s-triazine, with the English name Cyanuricfluoride, CAS number 675-14-9, molecular formula C3F3N3, molecular weight 135.05, and the structural formula is as follows:

[0003]

[0004] Cyanuric fluoride is an important intermediate for the synthesis of dyes, pesticides, and medicines. It is also an intermediate for perfluoroalkyl nitrile, an environmentally friendly insulating gas that replaces sulfur hexafluoride. Specifically, cyanuric fluoride can be used to synthesize fluorinated s-triazine reactive dyes. Since the electronegativity of fluorine atoms is higher than that of chlorine atoms, fluorinated s-triazine reactive dyes can significantly reduce the electron cloud density of the carbon atoms connected to them on the triazine ring, making the dyes more reactive while retaining other excellent properties of monochloro s-triazine reactive dyes. It has the advantages of energy saving, environmental protection, high stability, and high color fixation rate. It is an alternative and upgraded product for chlorinated s-triazine dyes.

[0005] The preparation methods of cyanuric fluoride can be divided into two categories:

[0006] The first type is the hydrogen fluoride route, which uses hydrogen fluoride and cyanuric chloride as raw materials. The reaction equation is as follows:

[0007]

[0008] German patents DE2643335 and DE2643251 reported that anhydrous hydrogen fluoride and cyanuric chloride with a molar ratio of 8 to 15:1 were reacted in batches in a reactor with a stirrer and a low-temperature reflux condenser at -20 to 80°C in the presence of a catalyst or without a catalyst to obtain the product cyanuric fluoride, which was distilled to obtain the product with a single-pass conversion rate of 79.7% and a total yield of ≥86%. This method is an intermittent operation, with hydrogen fluoride added in batches, and has the problems of long reaction time, difficulty in realizing automated production, low preparation efficiency, and a large amount of excess hydrogen fluoride, difficulty in recovery, and environmental unfriendliness.

[0009] The second preparation method is the alkali metal salt route, which uses alkali metal salts and cyanuric chloride as raw materials. Commonly used alkali metal fluoride salts include sodium fluoride, potassium fluoride, cesium fluoride, etc. The reaction equation of the synthesis route using sodium fluoride as the fluorinating agent is as follows:

[0010]

[0011] This route generally uses sulfolane and the like as solvents. U.S. Patent US06238328 reports a method for preparing cyanuric fluoride from cyanuric chloride using sodium fluoride in a dipolar aprotic solvent. Cyanuric chloride is added to a suspension of sodium fluoride in a dipolar aprotic solvent, and the suspension is heated to 120-220°C to react and prepare cyanuric fluoride. This method has the problems of high temperature and high equipment requirements, and the product cyanuric fluoride is easily decomposed into hydrogen fluoride, resulting in a decrease in the overall yield; the by-product solid salt waste such as sodium chloride is large and complex in composition, making it difficult to recycle and treat; the intermittent reaction is difficult to achieve automatic control; the reaction time is long and the preparation efficiency is low.

[0012] Chinese patent CN90103282.4 reports a method for preparing cyanuric fluoride at a relatively low temperature, which is to react cyanuric chloride or mixed chlorine, fluorinated-1,3,5-triazine with at least an equivalent amount of sodium fluoride, potassium fluoride or cesium fluoride or an optional mixture of these alkali metal fluorides in a non-protonic dipole liquid (tetrahydrothiophene sulfone, i.e. cyclopentane) at a temperature of 30 to 110°C to produce cyanuric fluoride. This method has the problems of difficulty in recovering the solvent cyclopentane and low recovery rate; high reaction temperature, resulting in the product cyanuric fluoride being easily decomposed into hydrogen fluoride, and the overall yield is reduced; and the by-product solid salt waste such as sodium chloride is large, complex in composition, and difficult to recover and treat.

[0013] The existing methods for preparing cyanuric fluoride may have problems such as low heat and mass transfer efficiency, difficult to control reaction rate, and many by-products; or there may be problems such as excessive amount of raw material hydrogen fluoride, difficulty in recovery, and environmental unfriendliness; or there may be problems such as uneven dispersion of solid alkali metal salt raw materials and long reaction cycle; or there may be problems such as easy agglomeration in production due to solid raw materials and by-products, causing equipment blockage and low yield; or there may be problems such as intermittent reaction and difficulty in achieving continuous industrial production. Summary of the invention

[0014] In order to solve the above technical problems, the present invention proposes a method for preparing cyanuric fluoride which has simple process, low cost, less three wastes, high product yield, is suitable for industrial production, does not require a catalyst, has a short reaction time and a high raw material conversion rate.

[0015] The objective of the present invention is achieved through the following technical solutions:

[0016] A method for preparing cyanuric fluoride comprises the following steps:

[0017] S1. Preparation of cyanuric chloride solution: dissolving cyanuric chloride in a solvent to obtain a cyanuric chloride solution;

[0018] S2. Preparation of mixed gas: Fluorine gas is diluted with inert gas to obtain a mixed gas;

[0019] S3. Fluorination reaction: In a continuous microreactor, the cyanuric chloride solution reacts with the fluorine gas in the mixed gas to generate cyanuric fluoride.

[0020] The reaction equation of the fluorination reaction of the present invention is as follows:

[0021]

[0022] The fluorination reaction of the present invention is an exothermic reaction. If the reaction system has a "hot spot" locally without control, the overall temperature will rise rapidly, causing side reactions such as chain breaking and rearrangement, affecting the product yield. Preferably, the fluorination reaction in step S3 includes a first stage reaction and a second stage reaction, and the first stage reaction temperature T1 ≤ the second stage reaction temperature T2. More preferably, the second stage reaction temperature T2 is 0 to 10°C higher than the first stage reaction temperature T1.

[0023] Preferably, the continuous microreactor is a microchannel reactor. The microchannel reactor can effectively improve the reaction rate of the reaction of the present invention, and can inhibit the occurrence of side reactions, thereby obtaining higher reaction selectivity and yield. More preferably, the continuous reactor is a gas-liquid phase microchannel reactor.

[0024] The gas-liquid phase microchannel reactor is divided into two sections. The first section of the microchannel reactor is a chip-type microchannel reactor, and the channel shape is a heart-shaped, diamond-shaped or internally provided with a baffle structure, and the channel diameter is 0.5 to 10 mm, preferably 0.5 to 3 mm. The first section of the microchannel reactor can enhance the raw material mixing effect; the second section of the microchannel reactor is a coil-type microchannel reactor, and the channel shape is a simple shape such as a cylindrical or rectangular parallelepiped shape, and the channel diameter is 0.5 to 10 mm, preferably 0.5 to 3 mm. Compared with traditional reactors such as kettle reactors, the reaction time of the reaction of the present invention can be greatly shortened. Preferably, the reaction temperature T1 of the first section of the reaction is -20 to 50 ° C, and the reaction time is 3 to 60 s; the reaction temperature T2 of the second section of the reaction is 0 to 50 ° C, and the reaction is 3 to 60 s.

[0025] In the preparation method of the present invention, the solvent can dissolve the raw material cyanuric chloride or form a suspension with the raw material, and does not react with the raw material. Preferably, the solvent is selected from at least one of halogenated alkanes, acids or anhydrides, nitrogen-containing compounds, and polar solvents. More preferably, the halogenated alkane solvent is selected from at least one of 1,1,2-trifluoro-1,2,2-trichloroethane or perfluorohexane; the acid or anhydride solvent is selected from at least one of formic acid, acetic acid or trifluoroacetic acid; the nitrogen-containing compound solvent is selected from at least one of acetonitrile, N,N-dimethylformamide or N,N-dimethylacetamide; the polar solvent is selected from at least one of sulfolane or a derivative of sulfolane.

[0026] The amount of the solvent used is not particularly limited. The cyanuric chloride is dissolved in the solvent to form a cyanuric chloride solution. The lower the content of cyanuric chloride in the cyanuric chloride solution, the more uniform the dispersion and the higher the reaction selectivity. However, if the content of cyanuric chloride is low, the solvent separation / recovery treatment volume will be relatively large, and separation / recovery is not economical. The molar concentration of cyanuric chloride in the cyanuric chloride solution is 0.1 to 3 mol / L, preferably 0.2 to 2 mol / L.

[0027] The volume percentage of fluorine gas in the mixed gas is 1% to 30%, preferably 3% to 15%. The inert gas is selected from at least one of nitrogen, argon and helium; preferably, the inert gas is nitrogen.

[0028] In the preparation method of the present invention, when the molar ratio of cyanuric chloride to fluorine gas is too low, the substrate cyanuric chloride will not be completely fluorinated, resulting in a low molar yield of the target product cyanuric fluoride; if the molar ratio is too high, the substrate will produce partial chain scission and rearrangement reactions, resulting in more by-products, resulting in a decrease in yield. Specifically, the molar ratio of cyanuric chloride to fluorine gas is 1: (1.5-5); preferably 1: (1.5-2.8); more preferably 1: (1.6-2.0); the reaction pressure of the fluorination reaction is 0.1-1.5 MPa, preferably 0.2-1.0 MPa.

[0029] The preparation method of the present invention is a continuous flow micro-reaction process, which has the advantages of enhanced heat transfer, enhanced mass transfer, and is conducive to automatic control, and is particularly suitable for high-risk chemical processes such as fluorination and nitration. Preferably, the cyanuric chloride solution can be precooled before the reaction, and the precooling temperature T0 ≤ the first stage reaction temperature T1.

[0030] Furthermore, the preparation method of the present invention comprises the following steps:

[0031] S1. Preparation of cyanuric chloride solution: dissolving cyanuric chloride in a solvent to obtain a cyanuric chloride solution;

[0032] S2. Preparation of mixed gas: Fluorine gas is diluted with inert gas to obtain a mixed gas;

[0033] S3. Fluorination reaction: The cyanuric chloride solution prepared in step S1 is passed through the precooling module of the first microchannel reactor, and after it is cooled to the precooling temperature T0, T0 is -20 to 50°C, it is passed through the mixer to mix with the mixed gas prepared in step S2, and then passed through the reaction module of the first microchannel reactor to react, the first reaction temperature T1 is -20 to 50°C, and the reaction time is 3 to 60s; then passed through the second microchannel reactor to react, the second reaction temperature T2 is 0 to 50°C, and the reaction is 3 to 60s to obtain a crude product;

[0034] S4. Product purification: The crude product obtained in step S3 is purified by distillation to obtain high-purity cyanuric fluoride.

[0035] Specifically, in step S3, the flow rate of the mixed gas is 10 to 3000 L / h; preferably, the flow rate of the mixed gas is 50 to 1200 L / h;

[0036] The reaction modules of the first-stage microchannel reactor and the second-stage microchannel reactor are respectively composed of 1 to 20 microchannel reactor modules connected in series.

[0037] The reaction product obtained in step S3 includes a gaseous material flow and a liquid material flow. Wherein, the gaseous material flow includes an inert gas, an incompletely reacted fluorine gas and a byproduct chlorine. A small amount of incompletely reacted fluorine gas is converted into a solid fluoride as a byproduct, the remaining inert gas is vented or recycled, and the chlorine is collected as a byproduct. The liquid material flow includes cyanuric fluoride, a solvent, an incompletely reacted raw material cyanuric chloride, and a byproduct difluoromonochloro-s-triazine and a fluorodichloro-s-triazine. After the product cyanuric fluoride is purified, other liquid materials can be recycled. Specifically, the solvent, the incompletely reacted raw material cyanuric chloride, the byproduct difluoromonochloro-s-triazine and the fluorodichloro-s-triazine can be re-entered into the reaction system for recycling.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The preparation method of the present invention uses highly active fluorine gas, does not require a catalyst, has a short reaction time and high efficiency;

[0040] 2. The preparation method of the present invention adopts a continuous microreactor, which has the function of enhancing mass transfer and heat transfer, reducing the side reactions of the reaction, and improving the selectivity of the reaction. The total yield can reach 99%;

[0041] 3. The byproduct chlorine gas of the present invention can be recycled and reused, and the byproducts difluoromonochloro-s-triazine and monofluorodichloro-s-triazine can be refluxed with the solvent for reuse, and there is basically no waste discharge. This is an economical, efficient, green chemical synthesis process with a prospect for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Attached Figure 1 This is a flow chart of the preparation process of Example 1 of the present invention. DETAILED DESCRIPTION

[0043] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all possible alternatives, improvements and equivalents within the scope of the claims.

[0044] Example 1

[0045] This embodiment uses a gas-liquid phase microreactor, and the first stage microchannel reactor is three Advanced-Flow TM The microchannel reactor formed by the combination of G2 silicon carbide material "heart-shaped" channel module chips has a liquid holding capacity of 100mL; the second microchannel reactor is a homemade coil reactor with a monel material cylindrical channel, with an inner channel diameter of 3mm and a reaction section liquid holding capacity of 100mL.

[0046] S1. Preparation of cyanuric chloride solution: Under nitrogen protection, 1000 mL of perfluorohexane and 156.4 g (0.85 mol) of cyanuric chloride were added to a container with a thermometer and a stirrer, and stirred continuously to obtain a cyanuric chloride solution having a cyanuric chloride concentration of 0.85 mol / L;

[0047] S2. Preparation of mixed gas: Fluorine gas (F2 content ≥ 99%) is diluted with high-purity nitrogen (N2 content ≥ 99.999%) to form a fluorine / nitrogen mixed gas, and a mixed gas with a fluorine gas volume percentage of 7.5% is prepared by partial pressure method;

[0048] S3. Fluorination reaction: The cyanuric chloride solution (23) prepared in step S1 is introduced into the precooling module (31) of the first microchannel reactor (3) by a pump for precooling, the precooling temperature T0 is 5°C, and after precooling, it enters the mixer (2) and the flow rate is controlled to be 1L / h; the mixed gas (13) prepared in step S2 is metered by a flow meter and enters the mixer (2) and the flow rate is controlled to be 400L / h; the molar ratio of cyanuric chloride to fluorine gas is 1:1.6; the cyanuric chloride solution and the mixed gas are mixed in the mixer (2) to form a product Stream A is introduced into the reaction module (32) of the first-stage microchannel reactor, and the gas-liquid two-phase reacts in the reaction module (32). The first reaction temperature T1 is controlled to be 10° C. and the reaction time is 7.9 s by adjusting the jacket refrigerant temperature of the first-stage microchannel reactor (3). Stream A is then introduced into the second-stage microreactor (4) for further reaction for 7.9 s, and the second reaction temperature T2 is 25° C. The reaction pressure of the entire reaction is 0.8 MPa. After the reaction is completed, the reaction product mixture stream (51) is discharged through the back pressure valve (5);

[0049] S4. Product purification: The liquid in the reaction product obtained in step S3 is separated by a distillation device.

[0050] 113.5 g (0.84 mol) of the target product cyanuric fluoride was obtained. The molar yield of the target product cyanuric fluoride was calculated to be 98.82% (calculated as cyanuric chloride) or 94.38% (calculated as fluorine gas).

[0051] The preparation process flow chart of Example 1 is as follows Figure 1As shown in Example 1, the present invention adopts a fluorine gas direct fluorination method, coupled with a two-stage continuous flow micro-reaction process, does not require a catalyst, has a short reaction time, high efficiency, a one-step reaction synthesis, a simple separation process, does not generate solid waste, and a simple solvent recovery process. The solvent is recovered while the product is separated.

[0052] Comparative Example 1

[0053] S1. 156.4 g (0.85 mol) of cyanuric chloride was added to a dry special material tubular reactor with a water bath jacket, and then the reactor was purged with nitrogen for 30 minutes, and the reactor temperature was controlled at 17.5 ° C by the water bath jacket;

[0054] S2. Mixed gas preparation: the same operation as in Example 1;

[0055] S3. A fluorine / nitrogen mixture was introduced into the reactor at a flow rate of 400 L / h, and the reaction was carried out for 60 minutes. A total of 1.34 mol of fluorine was introduced, and the molar ratio of cyanuric chloride to fluorine was 1:1.6. The reactor outlet valve was controlled to control the reaction pressure to 0.8 MPa. The reaction tail gas was discharged after absorbing unreacted fluorine and by-products through the tail gas absorption system; and then nitrogen was introduced to purge the reaction tube for 30 minutes;

[0056] S4. Open the reactor, collect the product, and separate it through a distillation device to obtain 17.62 g (0.13 mol) of the target product cyanuric fluoride.

[0057] The molar yield of the target product cyanuric fluoride was calculated to be 15.29% (based on cyanuric chloride).

[0058] Comparative Example 1 uses a tubular reactor commonly used in laboratories to carry out a gas-solid reaction between fluorine gas and the substrate. Due to problems such as insufficient contact between the reactants, local overheating, low substrate conversion rate, and poor product selectivity, the yield is low.

[0059] Comparative Example 2

[0060] S1. Preparation of cyanuric chloride solution: the same operation as in Example 1;

[0061] S2. Mixed gas preparation: the same operation as in Example 1;

[0062] S3. Fluorination reaction: first, purge the material pipeline and the jacketed, mechanically stirred special material high-pressure reactor with nitrogen for 30 minutes; then use a pump to add the cyanuric chloride solution prepared in step S1 into the reactor through the first inlet of the jacketed, mechanically stirred special material high-pressure reactor; while starting the stirring, pass the mixed gas prepared in step S2 into the reactor through the underwater bubbling tube of the reactor, control the flow rate to 400L / h, react for 60 minutes, and pass a total of 1.34 mol of fluorine gas, with a molar ratio of cyanuric chloride to fluorine gas of 1:1.6; during the reaction, the reaction temperature is controlled to be 17.5°C by controlling the temperature of the reactor jacket water bath, and the reaction pressure is controlled to be 0.8MPa by controlling the gas phase outlet valve on the upper part of the reactor; the reaction tail gas is discharged after absorbing the unreacted fluorine gas and by-products through the tail gas absorption system; after the reaction is completed, nitrogen is passed into the reactor and pipeline for 30 minutes, and then the reaction product mixture stream D is discharged from the bottom outlet of the reactor;

[0063] S4. Product purification: the operation is the same as in Example 1.

[0064] 60.75 g (0.45 mol) of the target product cyanuric fluoride was obtained. According to calculation, the molar yield of the target product cyanuric fluoride was 52.94% (based on cyanuric chloride).

[0065] Comparative Example 2 adopts a high-pressure reactor commonly used in laboratories to carry out a gas-liquid reaction between fluorine gas and the substrate solution. The traditional jacketed reactor has poor heat transfer effect, insufficient gas-liquid contact by bubbling, and poor mass transfer effect due to "hot spots", resulting in poor selectivity and other problems, so the yield is low.

[0066] Comparative Example 3

[0067] S1. Preparation of cyanuric chloride solution: the same operation as in Example 1;

[0068] S2. Preparation of fluorination reagent: Mix anhydrous hydrogen fluoride (GB7746 / T industrial first-class product, HF content w% ≥ 99.98%) with nitrogen to prepare a mixed gas with a volume percentage of hydrogen fluoride of 15%;

[0069] S3. Fluorination reaction: The operation is the same as in Example 1, except that the molar ratio of cyanuric chloride to hydrogen fluoride is 1:3.2, and the reaction temperature is 25 ° C;

[0070] S4. Product purification: the operation is the same as in Example 1.

[0071] 63.3 g (0.47 mol) of the target product cyanuric fluoride was obtained. According to calculation, the molar yield of the target product cyanuric fluoride was 55.29% (based on cyanuric chloride).

[0072] Although Comparative Example 3 also uses a microchannel reactor to carry out gas-liquid phase reaction to enhance heat and mass transfer, it uses a hydrogen fluoride route and uses hydrogen fluoride as a fluorinating agent, which has low reaction activity, low substrate conversion rate, and low yield.

[0073] Embodiment 2 to Embodiment 9

[0074] The operation steps of Examples 2 to 9 are the same as those of Example 1, except that the solvent is changed and other operations remain unchanged.

[0075] The molar yields of the target product cyanuric fluoride in Examples 2 to 9 are shown in Table 1 below.

[0076] Table 1 Molar yield of target product cyanuric fluoride in Examples 2 to 9

[0077] Serial number Solvents Molar yield of cyanuric fluoride (%) Example 2 Anhydrous formic acid 94.11 Example 3 Anhydrous acetic acid 94.11 Example 4 Trifluoroacetic acid 95.29 Example 5 Freon-113 97.65 Example 6 Anhydrous acetonitrile 90.59 Example 7 N,N-Dimethylformamide 91.76 Example 8 N,N-Dimethylacetamide 90.59 Example 9 Sulfolane 91.76

[0078] As can be seen from Table 1, the preparation method can obtain the target product in a relatively high yield by using halogenated alkanes, acids or anhydrides, nitrogen-containing compounds and polar solvents.

[0079] Comparative Example 4

[0080] S1. Preparation of cyanuric chloride solution: The operation is the same as in Example 1, except that the solvent is n-hexane, and the other operations remain unchanged;

[0081] S2. Mixed gas preparation: the same operation as in Example 1;

[0082] S3. Fluorination reaction: The operation is the same as in Example 1;

[0083] S4. Product purification: the operation is the same as in Example 1.

[0084] 21.2 g (0.16 mol) of the target product cyanuric fluoride was obtained. According to calculation, the yield of the target product cyanuric fluoride was 18.82% (based on cyanuric chloride).

[0085] Comparative Example 4 uses n-hexane as solvent, and the yield is relatively low. It is speculated that part of the solvent n-hexane reacts with fluorine gas before the substrate cyanuric chloride, resulting in a decrease in substrate conversion rate and selectivity, resulting in a low yield.

[0086] Example 10 to Example 13

[0087] The operation steps of Examples 10 to 13 are the same as those of Example 1, with the only difference being that the flow rate of the mixed gas in step S3 is changed, thereby changing the molar ratio of cyanuric chloride to fluorine gas, and other operations remain unchanged.

[0088] The yield of the target product cyanuric fluoride (calculated as cyanuric chloride) is shown in Table 2.

[0089] Table 2 Molar yield of target product cyanuric fluoride of Example 10 to Example 13

[0090]

[0091] As can be seen from Examples 10 to 13, the molar ratio has a significant effect on the preparation method. When the molar ratio of cyanuric chloride to fluorine gas is 1: (1.5-5), the product cyanuric fluoride can be prepared at a higher yield. When the molar ratio is lower than 1: 1.5, the molar yield of the target product cyanuric fluoride is low because the substrate cyanuric chloride is not completely fluorinated. As the molar ratio increases, the substrate will produce partial chain breaking and rearrangement reactions, resulting in more by-products, leading to a decrease in yield. However, as the molar ratio increases, the reaction time is shortened, and the substrate and fluorine gas are removed from the reactor in time to terminate the reaction, which is less than the by-products that may be produced in theory, so the yield does not decrease rapidly, but too much excess fluorine gas will increase the cost.

[0092] Embodiment 14

[0093] S1. Preparation of cyanuric chloride solution: Under nitrogen protection, 1000 mL of perfluorohexane and 110.6 g (0.6 mol) of cyanuric chloride were added to a container with a thermometer and a stirrer, and stirred continuously to obtain a perfluorohexane solution with a cyanuric chloride concentration of 0.6 mol / L;

[0094] S2. Preparation of mixed gas: The operation is the same as in Example 1, except that: the volume percentage of fluorine gas in the mixed gas is 15%;

[0095] S3. Fluorination reaction: The operation is the same as in Example 1, except that: the flow rate of cyanuric chloride solution is 1.0 L / h, the flow rate of the mixed gas is 150 L / h, the molar ratio of cyanuric chloride to fluorine gas is 1:1.67, the first reaction temperature T1 is 15 ° C, the reaction pressure is 1.0 MPa, the reaction time in the first microchannel reactor (3) and the second microreactor (4) are 12.3 s, and the total reaction time is 24.6 s;

[0096] S4. Product purification: the operation is the same as in Example 1.

[0097] 80.1 g (0.59 mol) of the target product cyanuric fluoride was obtained. According to calculation, the molar yield of the target product cyanuric fluoride was 98.33% (based on cyanuric chloride).

[0098] Example 15 to Example 21

[0099] The operating steps of Examples 15 to 21 are the same as those of Example 14, with the only difference being that the precooling temperature T0 is the same as the first stage reaction temperature T1, the reaction temperature of step S3 is changed, and other operations remain unchanged.

[0100] The molar yield of the target product cyanuric fluoride (calculated as cyanuric chloride) is shown in Table 4.

[0101] Table 4 Molar yield of target product cyanuric fluoride of Examples 15 to 21

[0102] Serial number <![CDATA[T1,℃]]> <![CDATA[T2,℃]]> Molar yield of cyanuric fluoride (%) Embodiment 15 -5 25 91.67 Example 16 0 25 93.33 Embodiment 17 20 25 98.33 Embodiment 18 30 25 91.67 Embodiment 19 20 20 95.00 Embodiment 20 20 30 98.33 Embodiment 21 20 40 93.33

[0103] Comparative Example 5 to Comparative Example 8

[0104] The operating steps of Comparative Examples 5 to 8 are the same as those of Example 14, with the only difference being that the precooling temperature T0 is the same as the first stage reaction temperature T1, the reaction temperature of step S3 is changed, and other operations remain unchanged.

[0105] The molar yield of the target product cyanuric fluoride (calculated as cyanuric chloride) is shown in Table 5.

[0106] Table 5 Molar yield of target product cyanuric fluoride of Comparative Examples 5 to 8

[0107] Serial number <![CDATA[T1,℃]]> <![CDATA[T2,℃]]> Molar yield of cyanuric fluoride (%) Comparative Example 5 -25 -25 11.76 Comparative Example 6 -25 60 23.53 Comparative Example 7 20 -25 44.71 Comparative Example 8 20 80 38.82

[0108] From Examples 15 to 21 and Comparative Examples 5 to 8, it can be seen that the reaction temperature has a significant effect on the product yield. The target product can be prepared with a high yield when the reaction temperature is within the range of -5 to 40°C; the reaction temperature in Comparative Example 5 is too low, the reaction proceeds slowly, and the yield is low; the reaction temperature in Comparative Example 8 is too high, the reaction is violent, the by-products increase, the selectivity decreases, and the yield of the target product decreases. From Examples 17 and 20, it can be seen that the reaction temperature of the second-stage microreactor is 0 to 10°C higher than the reaction temperature of the first-stage microchannel reactor, which is particularly beneficial to the reaction and can obtain a higher yield.

[0109] Example 22 to Example 24

[0110] The operating steps of Examples 22 to 24 are the same as those of Example 14, with the only difference being that the flow rates of the raw material cyanuric chloride and the mixed gas in Step S3 are changed, thereby changing the total reaction time, and other operations remain unchanged.

[0111] The molar yield of the target product cyanuric fluoride (calculated as cyanuric chloride) is shown in Table 6.

[0112] Table 6 Molar yield of target product cyanuric fluoride of Example 22 to Example 24

[0113]

[0114] Embodiment 25

[0115] S1. Preparation of cyanuric chloride solution: The operation is the same as in Example 1, except that the solvent is perfluorohexane recovered after the reaction in Example 1. In addition to perfluorohexane, the recovered perfluorohexane also contains a small amount of incompletely reacted raw material cyanuric chloride, by-products difluoromonochloro-s-triazine and monofluorodichloro-s-triazine. Other operations remain unchanged.

[0116] S2. Mixed gas preparation: the same operation as in Example 1;

[0117] S3. Fluorination reaction: The operation is the same as in Example 1;

[0118] S4. Product purification: the operation is the same as in Example 1.

[0119] 114.2 g (0.846 mol) of the target product cyanuric fluoride was obtained. According to calculation, the total yield of the target product cyanuric fluoride was 99.53% (based on cyanuric chloride).

[0120] It can be seen from Example 25 that the recycled solvent contains a small amount of incompletely reacted raw material cyanuric chloride, by-products difluoromonochlorotriazine and monofluorodichlorotriazine. After participating in the reaction, the conversion rate, selectivity and reaction yield are all improved, indicating that the recovered solvent can be recycled, which can not only reduce emissions and reduce the impact on the environment, but also further reduce production costs.

[0121] Embodiment 26

[0122] S1. Preparation of cyanuric chloride solution: the same operation as in Example 1;

[0123] S2. Mixed gas preparation: the same operation as in Example 1;

[0124] S3. Fluorination reaction: The operation is the same as in Example 1, except that: the reaction is carried out only in the reaction module (32) of the first microchannel reactor, the flow rate of the cyanuric chloride solution is 0.5 L / h, the flow rate of the mixed gas is 200 L / h, the reaction time is 15.8 s, and the reaction temperature is 25 ° C;

[0125] S4. Product purification: the operation is the same as in Example 1.

[0126] 87.9 g (0.65 mol) of the target product cyanuric fluoride was obtained. According to calculation, the molar yield of the target product cyanuric fluoride was 76.47% (based on cyanuric chloride).

[0127] It can be seen from Example 26 that a continuous microreactor is also used to enhance mass transfer and heat transfer. The reaction is only carried out in the first microchannel reactor without the second microreactor temperature increase reaction. Although the total reaction time is 15.8s, the reaction is not fully activated, resulting in a decrease in the product yield.

[0128] Comparative Example 9

[0129] 156.4g (0.85mol) of cyanuric chloride was added to a three-mouth reactor made of polytetrafluoroethylene with mechanical stirring and condensation reflux; the reactor was placed in a cold bath, the temperature was controlled at -10 to -15°C, and 136.0g (6.80mol) of liquid anhydrous hydrogen fluoride was slowly added to immediately produce gaseous HCl, and the tail gas was absorbed by the alkali solution after condensation. After the addition of anhydrous hydrogen fluoride was completed, the reaction temperature was raised to room temperature, and the production of HCl was observed at the same time. After 6 hours, the reaction became significantly weaker. After another hour, the reaction was terminated when there was basically no HCl escaping. The reaction system was purged with nitrogen, and the crude product was taken out and separated by distillation to obtain 63.3g (0.47mol) of the target product cyanuric fluoride. The molar yield of the target product cyanuric fluoride was 52% (in terms of cyanuric chloride) or 19% (in terms of hydrogen fluoride).

[0130] Comparative Example 9 adopts the conventional hydrogen fluoride route to synthesize cyanuric fluoride. This method is intermittently operated, has a long reaction time, and uses an ordinary reactor, which has poor heat and mass transfer effects, resulting in problems such as poor conversion rate and selectivity. Therefore, the yield is low, and a large amount of hydrogen fluoride is in excess, so the yield based on hydrogen fluoride is even lower.

Claims

1. A method for preparing cyanuric fluoride, characterized in that: The preparation method comprises the following steps: S1. Preparation of cyanuric chloride solution: dissolving cyanuric chloride in a solvent to obtain a cyanuric chloride solution; S2. Preparation of mixed gas: Fluorine gas is diluted with inert gas to obtain a mixed gas; S3. Fluorination reaction: In a continuous microreactor, the cyanuric chloride solution reacts with the fluorine gas in the mixed gas to generate cyanuric fluoride.

2. The method for preparing cyanuric fluoride according to claim 1, characterized in that: The fluorination reaction in step S3 includes a first stage reaction and a second stage reaction, and the first stage reaction temperature T1 ≤ the second stage reaction temperature T2.

3. The method for preparing cyanuric fluoride according to claim 2, characterized in that: The second stage reaction temperature T2 is 0 to 10°C higher than the first stage reaction temperature T1.

4. The method for preparing cyanuric fluoride according to claim 1, characterized in that: The solvent is selected from at least one of halogenated alkanes, acids or acid anhydrides, nitrogen-containing compounds, and polar solvents.

5. The method for preparing cyanuric fluoride according to claim 1, characterized in that: The halogenated alkane solvent is selected from at least one of 1,1,2-trifluoro-1,2,2-trichloroethane or perfluorohexane; the acid or anhydride solvent is selected from at least one of formic acid, acetic acid or trifluoroacetic acid; the nitrogen-containing compound solvent is selected from at least one of acetonitrile, N,N-dimethylformamide or N,N-dimethylacetamide; the polar solvent is selected from at least one of sulfolane or a derivative of sulfolane.

6. The method for preparing cyanuric fluoride according to claim 1, characterized in that: The continuous microreactor is a microchannel reactor, and the diameter of the microchannel is 0.5-10 mm.

7. The method for preparing cyanuric fluoride according to claim 1, characterized in that: The molar concentration of cyanuric chloride in the cyanuric chloride solution is 0.1-3 mol / L; the volume percentage of fluorine gas in the mixed gas is 1%-30%.

8. The method for preparing cyanuric fluoride according to claim 1, characterized in that: The molar ratio of cyanuric chloride to fluorine gas is 1:(1.5-5), and the reaction pressure is 0-1.5 MPa.

9. The method for preparing cyanuric fluoride according to claim 3, characterized in that: The reaction temperature T1 of the first stage reaction is -20 to 50°C, and the reaction time is 3 to 60s; the reaction temperature T2 of the second stage reaction is 0 to 50°C, and the reaction time is 3 to 60s.

10. The method for preparing cyanuric fluoride according to claim 3, characterized in that: The cyanuric chloride solution is precooled before the reaction, and the precooling temperature T0 is ≤ the first stage reaction temperature T1.

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